I'm getting ready to do a swap out of my cat and try using a stock cat that has been gutted since mine is clogging up. Are there any gaskets that go on either end of the pipe before I bolt it on? Or do I just use what's there?

 

There's a flat gasket in the front & a half round donut in the back.
You could possibly reuse them, but
it's a good idea to get new ones unless you don't mind doing it twice.

 

Do you know what the name of the parts and the parts number are or a link to them?